The surprise is that Volkswagen’s shares fell only 10% as the cheating affair deepened in several ways. First, the scandal now covers emissions of carbon dioxide, or CO2, not only nitrogen oxide. Second, some petrol engines are now involved. Third – perhaps most importantly for shareholders who hope VW can recover quickly – the company still seems incapable of giving a straightforward account of what its own investigation has uncovered.

Tuesday evening’s statement contained the obligatory expressions of regret and commitment to transparency. Indeed, Matthias Müller, the executive shoved into the hot seat in the first week of the crisis, opted for pomposity overdrive.

“From the very start I have pushed hard for the relentless and comprehensive clarification of events,” he declared. “We will stop at nothing and nobody. This is a painful process, but it is our only alternative. For us, the only thing that counts is the truth.”

What, though, did VW actually say beyond the confession that “based on present knowledge” 800,000 vehicles have been affected? Almost nothing. Were cheat devices attached to the vehicles, or were real CO2 emissions disguised by other means? How many petrol cars are affected? Does the phrase “present knowledge” mean most cars in VW’s fleet are in the clear, or that they haven’t yet been examined for CO2? And, since the word “irregularities” is so vague, how severely wrong is the published CO2 data? None of these issues were addressed.

A little reticence is understandable while investigations continue but it is not unreasonable to expect VW to explain why it can’t answer questions that would occur to most readers of its statement.

More disgracefully from the point of view of shareholders, the company failed to explain how it derived its estimate that the latest revelations will cost “approximately €2bn”. Does that figure merely cover tax credits that now would appear to have been unfairly earned? Analysts assume so, in which case there could also be a wave of claims from consumers who were encouraged to buy VW vehicles on the basis of bogus claims about fuel efficiency. Analysts at Exane BNP Paribas, for example, added €4bn for recall and compensation costs for customers. That assumption sounds fair. The point, though, is that VW ought to be able say what its €2bn covers and what it doesn’t.

Sadly, though, whatever Müller says about following a “path of clarification and transparency”, ambiguity has been the hallmark of VW’s statements for the past month. If that’s the approach, outsiders will naturally assume this scandal could become substantially worse.

Germany’s chancellor, Angela Merkel, must be tearing her hair out. She is trying to deflect damage to the country’s industrial and engineering reputation but is obliged to defend, half-heartedly, a VW boardroom that still seems to be in a state of shock.

Merkel could help herself by insisting that VW – a company whose senior ranks are dominated by a cosy-looking alliance of family shareholders, local Saxony officials and trade unionists – imports some senior independent outsiders to oversee the inquiry. The company’s current crew seems to prefer obfuscation and is making matters worse.

M&S is now buying at sharper prices by designing more clothes inhouse and is finding savings in its supply chain. Both ingredients were missing in the early years of Marc Bolland’s reign but, finally, the chief executive is in the expectation-beating game. Last year’s increase in gross margins was 1.9 percentage points and Bolland thinks M&S will beat that figure this year

If the well-paid Lindsey brothers, Neal and Mark, are responsible for injecting some Next-style rigour into M&S’s sourcing network, they’re earning their keep. When your turnover in general merchandise is £4bn, percentage points matter.

Yet a 1.2% fall in like-for-like sales in general merchandise – indeed, a 1.9% tumble in the second quarter – can’t be ignored. Remember, these are declines upon declines. Perpetual loss of market share in clothing is not a long-term option for M&S. One day the sagging sales line may have to be confronted head-on by recycling efficiency savings into lower prices for customers.

That date with destiny, though, is not now. Today, the M&S arithmetic works. After a long period of heavy capital expenditure, the business is generating lots of cash – £256m in the six-month period – and debt is falling steadily, allowing a 6% hike in the dividend and, presumably, more share buybacks in time. The food division continues its winning ways and only the international side, inevitably hampered by Russia and currencies, is a drag. Bolland deserves more credit than he’s getting.